RPM is the Red Hat Package Manager. While it does contain Red Hat in the name, it is completely intended to be an open packaging system available for anyone to use. It allows users to take source code for new software and package it into source and binary form such that binaries can be easily installed and tracked and source can be rebuilt easily. It also maintains a database of all packages and their files that can be used for verifying packages and querying for information about files and/or packages.
Red Hat Software encourages other distribution vendors to take the time to look at RPM and use it for their own distributions. RPM is quite flexible and easy to use, though it provides the base for a very extensive system. It is also completely open and available, though we would appreciate bug reports and fixes. Permission is granted to use and distribute RPM royalty free under the GPL.
RPM can even provide an excellent method to upgrade an existing system. The database won't be as up to date as a machine that was completely installed with RPM, but it will still contain anything installed with RPM. It can also be used to package commercial software.